In an effort to reduce back pain through early intervention techniques, many investigators have focused upon heating a portion of the annulus fibrosus.
Some investigators have provided such heat by first inserting a probe into the nucleus pulposus section of an intervertebral disc and then heating the annulus fibrosus portion of the disc from that location.
Although this technique may provide therapy to the annulus fibrosus, it also requires puncturing the annulus fibrosus in another location, thereby increasing the risk of a later herniation.
U.S. Pat. No. 5,569,242 (“Lax”) discloses a radiofrequency (RF) probe for heating the exterior wall of the annulus fibrosus of a herniated disc. See FIG. 23 of Lax. Lax further discloses that the probe may include an insulator positioned between the electrode and adjacent tissue for protecting the adjacent tissue from heat produced by the electrode. See FIG. 9 of Lax. Lax further discloses a probe having a configuration wherein the electrode is spaced from the tissue to be treated. See FIG. 10 of Lax. Although Lax further discloses a roller element electrode having projections, Lax does not disclose any function of such projections. See FIG. 18 of Lax.
Lax does not disclose a means for aiding the insertion of the probe. Lax does not disclose a probe having an inflatable portion positioned between the target tissue and the electrode.
PCT Published Patent Application No. WO 02/28302 (“Brett”) also discloses a thermal therapy device adapted to exteriorly treat the intervertebral disc. One embodiment disclosed by Brett contains a distal end that is smoothly rounded for reaching the injury site without snagging and is thinner to provide easy insertion between tissue layers. Another embodiment contains a wedged portion that is expandable to protect adjacent non-target tissue. The FIG. 12 embodiment of Brett contains a malleable energy application region 350 that appears to allow the surface of the device through which energy flows to conform to the target tissue surface.
In sum, the devices disclosed by Lax and Brett are configured and adapted for treating an intervertebral disc from outside the disc, and each recognizes a need to protect adjacent or target tissue from overheating.